Hydraulically powered counter-blow hammer

ABSTRACT

A hydraulic counter-blow hammer having a hydraulic coupling system for making the tups move in opposite directions and a hydraulic retraction system for retracting the tups prior to a stroke. The hydraulic retraction system is combined with the hydraulic retraction system without there being hydraulic intercommunication between the two systems. Differential pistons are connected to the upper tup and the differential pistons have two working faces moving in two different but co-axial cylinders. One cylinder is in the hydraulic coupling system for coupling the lower tup to the upper tup and the other cylinder is in the hydraulic retraction system for retracting the upper tup.

States Patent 91 Schmoll et al.

[ HYDRAULICALLY POWERED COUNTER-BLOW HAMMER [75] Inventors: Heinz Schmoll, Huckeswagen; Dieter Jenke, Gruiten, both of Germany [73] Assignee: Schloemann Aktiengesellschait, Dusseldorf, Germany 221 Filed: No'v.23, 1971 211 AppLNos 201,439

[30] Foreign Application Priority Data [451 May 29,1973

Primary Examiner--Charles W. Lanham Assistant Examiner-Gene P. Crosby Attorney-Holman & Stern [57] ABSTRACT A hydraulic counter-blow hammer having a hydraulic coupling system for making the tups move in opposite directions and a hydraulic retraction system for retracting the tups prior to a stroke. The hydraulic retraction system is combined with the hydraulic retraction system without there being hydraulic intercommunication between the two systems. Differential pistons are connected to the upper tup and the differential pistons have two working faces moving in two different but co-axial cylinders. One cylinder is in the hydraulic coupling system for coupling the lower tup to the upper tup and the other cylinder is in the hydraulic retraction system for retracting the upper tup.

1 Claim, 1 Drawing Figure Pmfimmm 3', 735.631

INVENTOR HEINZ SCHMOLL E AL 1 HYDRAULICALLY POWERED COUNTER-BLOW HAWER The invention relates to a hydraulically powered counterblow hammer, the hydraulic coupling system (hydraulic coupling means) of which is combined with the hydraulic retraction system (hydraulic retraction means). The hammer has upper and lower movable tool-mounting members (which may be referred to as tups) which move in opposite directions.

Counter-blow hammers either operate as fully hydraulic hammers or compress a gas cushion via a hydraulic retraction system.

In one of the latter type of hydraulically coupled counter-blow hammers, the coupling piston for the lower tool-mounting member includes a differential piston. Hydraulic pressure on the annular face of the piston causes a gas cushion to. be compressed by the upper tup acting through the coupling system.

There is here no absolute separation between the coupling system and the retraction system, while in order to achieve a good seal what are generally referred to as moving packings are required in the lower differential piston.

The hydraulic retraction system may also take the form of a separate pair of pistons additional to the two displacement pistons of the hydraulic coupling. However, this arrangement is relatively costly.

The present invention provides a hydraulically powered counter-blow hammer having an upper movable tool-mounting member, a lower movable tool-mounting member, hydraulic coupling means for coupling the upperand lower tool-mounting members together for move-. ment in opposite directions, the hydraulic coupling means including first cylinders, hydraulic retraction means for retracting at least one of the tool-mounting members, the hydraulic retraction means including second cylinders, said second cylinders being co-axial with, but not in substantial fluid communication with, respective said first cylinders, and differential pistons connected to the upper toolmounting member, each-differential piston having two parts defining two respective working faces, a first part being received in a respective said first cylinder and forming part of the hydraulic coupling means and a second part being received in a respective said second cylinder and forming part of the hydraulic retraction means.

' 1n the hammer of the invention, the couplingand retraction means are completely separated from each other. A leak in one system cannot influence the other system, while yet retaining a hydraulic coupling function. The packings in the respective cylinders can be located at the ends and can therefore be stationary. As a result they are not subject to inertial loadings, and are easily replaced. The part of the differential piston which plunges from the upper cylinder into the lower cylinder may be protected from the exterior by an intermediate piece which covers the two cylinder ends, e.g., by an easily removable sleeve. This cylinder arrangement bridges the dead space between the retraction drive for the uppertool-mounting member and the coupling cylinder in the base plate, without additional space being required on the hammer. In general, the

co-axial cylinder arrangement need not increase the height of the hammer.

One embodiment of the invention will now be described, by way of example, with reference to the accompanying drawing.

The drawing shows, in diagrammatic form, a vertical counter-blow hammer. Stands 2 are mounted on a base plate 1 and carry a cylinder 3 at their top ends. Connecting lines 5 join the cylinder 3 to gas containers 6 located in the stands 2. A differential piston 7 of the upper tup (upper movable tool-mounting member) slides within the cylinder 3. The cylinder chambers 8 and 8a are connected together so that the tup shaft constitutes the effective piston surface for the gas cushion. The lower tup (lower movable tool-mounting member) 9 slides in guides on the stands 2 (which slides are not shown in detail in the drawing) and rests through a spherically ended pushrod 10 on a piston 11 which plunges into a coupling cylinder 12 arranged in the base plate 1. To the right and left of the coupling cylinder 12 are provided further vertical axis coupling cylinders 13 and 14, these being located either in the base plate 1 or in the stands 2 which rest thereon. The coupling cylinders 12, 13, 14 are connected together by lines 15.

Retraction cylinders 16, 17 are arranged on each of the stands 2, co-axial with and above the respective coupling cylinders 13 and 14. Differential pistons 18 and 19 plunge into the retraction cylinders 16 and 17. The seal between the pistons 18 and 19 and the retraction cylinders 16 and 17 is effected by means of packings 20, 21 provided in the cylinders. The lower piston portions 18a, 19a, which project from the retraction cylinders 16, 17, plunge into the coupling cylinders 13, 14 located therebelow. Corresponding stationary packings 21, 22 seal the lower piston portions 18a, 19a to the coupling cylinders 13, 14. The space between the coupling and retraction cylinders 13, 16 or 14, 17 which are arranged one above the other is covered by a sleeve 23 which protects the piston portions 180, 19a against the ingress of dirt.

The retraction cylinders 16, 17 are connected through lines 24 with a control device (not shown) which is in turn connected to a fluid reservoir and pump or a pressure accumulator (not shown), so that at certain times the fluid located in the retraction cylinders 16, 17 and line 24 is pressurized or relieved of pressure.

Pushrods 25 are located between the upper hammer tup (7) and the difierential pistons 18 and 19; both ends of the pushrods 25 are spherical and abut spherical sockets in the differential pistons 18, 19 and in buffer plates on the upper hammer tup (7).

The operation of this embodiment is as follows:

The control device (not shown) supplies hydraulic pressure to the lines 24 and thus to the retraction cylinders 16, 17, which hydraulic pressure acts on the annular, differential working faces of the differential pistons 18, 19. The differential pistons 18, 19 move upwards and act through the pushrods 25 to move the upper hammer tup (7) upwards. The upper tup differential piston 7 thus compresses the gas cushions in the gas containers 6.

As the lower piston portions 18a, are raised out of the coupling cylinders 13, 14, the hydraulic coupling between the coupling cylinder 12 and the coupling cylinders 13, 14 permits the piston 1 1 to drop; this ensures that the upper and lower hammer tups (7), 9 move in opposite directions.

The control device (not shown) now opens ports of sufficiently large cross-section to drain the hydraulic fluid from the retraction cylinders 16, 17. The upper tup (7) is driven downwards by the expansion of the compressed gas cushions in the gas containers 6 while the lower tup 9 is driven upwards through the hydraulic coupling between the coupling cylinders 12, 13 and 14.

The cycle is then repeated.

We claim:

1. A hydraulically powered counter-blow hammer having an upper movable tool-mounting member,

a lower movable tool-mounting member,

hydraulic coupling means for coupling the upper and lower tool-mounting members together for movement in opposite directions, the hydraulic coupling means including first cylinders,

hydraulic retraction means for retracting at least one of the tool-mounting members, the hydraulic retraction means including second cylinders, said second cylinders being co-axial with, but not in substantial fluid communication with, respective said first cylinders,

diflerential pistons connected to the upper toolmounting member, each differential piston having two parts defining two respective working faces, a first part being received in a respective said first cylinder and forming part of the hydraulic coupling means and a second part being received in a respective said second cylinder and forming part of the hydraulic retraction means, and

means for moving the upper and lower tool-mounting members together to effect a working stroke.

II II I 

1. A hydraulically powered counter-blow hammer having an upper movable tool-mounting member, a lower movable tool-mounting member, hydraulic coupling means for coupling the upper and lower toolmounting members together for movement in opposite directions, the hydraulic coupling means including first cylinders, hydraulic retraction means for retracting at least one of the tool-mounting members, the hydraulic retraction means including second cylinders, said second cylinders being co-axial with, but not in substantial fluid communication with, respective said first cylinders, differential pistons connected to the upper tool-mounting member, each differential piston having two parts defining two respective working faces, a first part being received in a respective said first cylinder and forming part of the hydraulic coupling means and a second part being received in a respective said second cylinder and forming part of the hydraulic retraction means, and means for moving the upper and lower tool-mounting members together to effect a working stroke. 